1. Field of the Invention
The present invention relates to a machine having an oil seal which includes a cover for covering the oil seal mounted between a rotating shaft and a housing, and a retaining member for retaining the oil seal at a set position in a through hole in the interior of the cover.
2. Description of the Related Art
Conventionally, in a machine, such as an internal combustion engine, having a rotating shaft and a housing having a through-hole through which the rotating shaft is passed, an oil seal is mounted between the rotating shaft and a circumferential wall of the through-hole. The oil seal prevents lubricating oil which is supplied to a bearing portion for supporting the rotating shaft to the outside of the housing from leaking through the through-hole. Then, in order to prevent the decrease in sealing function of the oil seal that would occur when the oil seal is axially dislocated within the through-hole due to vibrations of the internal combustion engine, the oil seal is press fitted in the through-hole with a relatively large press-fit margin, or there is provided a member for preventing the occurrence of such a deviation.
An engine for an outboard motor disclosed in JP-A-10-317935 as an example of the latter case is structured as follows. One end portion of a crankshaft which is oriented vertically extends upwardly through a boss portion for a crankshaft-bearing formed at an upper portion of a crankcase. A bearing for supporting the crankshaft is disposed at a lower portion in the interior of the boss portion. An oil seal is disposed in an upper portion in the interior of the boss portion. Then, a breather cover closes a breather chamber adjacent to the boss portion. An extending portion formed on a circumferential portion of the breather cover covers above the oil seal, whereby even if the oil seal is dislocated upwardly in the interior of the boss portion, the oil seal is brought into abutment with the extending portion to thereby prevent the dislocation of the oil seal from the boss portion.
As is disclosed in the above Japanese unexamined patent publication, the decrease in sealing function of the oil seal due to the dislocation thereof is prevented with the simple construction in which the retaining member is provided for preventing the dislocation of the oil seal. In a machine in which an oil seal is covered entirely by a cover after the oil seal is mounted on the machine, however, since the retaining member is also covered by the cover, the retaining member is completely covered by the cover after the cover is mounted, and therefore that the retaining member is mounted cannot be confirmed from the outside of the cover. Alternatively, since the retaining member is hidden by another member disposed in the vicinity thereof, it becomes extremely difficult to confirm the attachment of the retaining member from the outside of the cover. In order to implement the confirmation, the cover needs to be removed, thus causing a problem that a certain length of time is required to confirm that the retaining member is mounted.
The invention was made in view of these situations, and a common object of first to sixth aspects of the invention is to construct a machine having an oil seal in which a cover is provided for covering the entirety of the oil seal such that whether or not a retaining member for retaining the oil seal at a set position in a through-hole is mounted can easily be confirmed from the outside of the cover so as to improve the working efficiency in confirming that the retaining member is mounted.
An object of the second to fifth aspects of the invention is to make it possible to confirm that the retaining member is mounted with a simple construction.
In addition, an object of the third aspect of the invention is to reduce limitations to the layout of members provided in the interior of the cover where the retaining member is mounted despite the fact that the retaining member is fixed by a fixing member.
Furthermore, an object of the fourth aspect of the invention is to make it possible to mount the retaining member even after the cover has been mounted to thereby improve the working efficiency in mounting the retaining member.
Moreover, an object of the sixth aspect of the invention is not only to enhance the rigidity of the retaining member but also to improve the working efficiency in mounting the retaining member.
According to the first aspect of the invention, there is provided a machine having an oil seal comprising a housing having a through-hole formed therein for allowing a rotating shaft to pass therethrough, an oil seal mounted between the rotating shaft and a circumferential wall of the through-hole and a cover mounted on the housing so as to abut with a mating surface of the housing in such a manner as to cover the entirety of the oil seal, wherein a retaining member which occupies a retaining position to cover at least part of the oil seal in the interior of the housing is fixed by fixing member so that the oil seal is retained at an axial set position in the through-hole by the retaining member, and wherein confirmation means is provided for confirming the attachment of the retaining member from the outside of the cover.
According to the first aspect of the invention, even if the oil seal is caused to move axially in the through hole due to vibrations of the housing, since the oil seal is retained at the axial set position in the through hole by the retaining member, the decrease in sealing function of the oil seal is prevented that would otherwise be caused by the movement. In addition, despite the fact that the retaining member is adapted to cover the oil seal in the interior of the cover which is brought into abutment with the mating surface of the housing so as to cover the entirety of the oil seal, since there is provided the confirmation means, whether or not the retaining member is mounted can easily be confirmed from the outside of the cover. As a result, since there is provided the confirmation means for confirming that the retaining member is mounted from the outside of the cover, that the retaining member is mounted can easily be confirmed even after the cover is mounted, whereby the working efficiency in confirming that the retaining member is mounted can advantageously be improved.
According to the second aspect of the invention, there is provided a machine having an oil seal as set forth in the first aspect of the invention, wherein the confirmation means is an extension of the retaining member which extends to the outside of the cover.
According to the second aspect of the invention, whether or not the retaining member is mounted is easily confirmed by seeing whether or not the extension extends to the outside of the cover. As a result, in addition to the advantage provided under the first aspect of the invention, the confirmation that the retaining member is mounted can advantageously be eased with the simple construction in which part of the retaining member is allowed to extend to the outside of the cover.
According to the third aspect of the invention, there is provided a machine having an oil seal as set forth in the second aspect of the invention, wherein the retaining member is fixed to the housing at the extension by the fixing member.
According to the third aspect of the invention, the retaining member is fixed to the housing outside the housing. As a result, in addition to the advantage provided under the second aspect of the invention, since the retaining member is fixed outside the cover, even if the fixing member is not provided inside the cover or is provided inside the cover, the number of fixing members can be reduced, and limitations to the layout of members provided in the interior of the cover by the fixing member or effects of provision of the fixing member on the members can be reduced, in turn, whereby a large degree of freedom in the layout of the members can advantageously be secured.
According to the fourth aspect of the invention, there is provided a machine having an oil seal as set forth in the third aspect of the invention, wherein the retaining member can be inserted into the interior of the cover from a gap formed between the cover and the mating surface of the housing in association with the elastic deformation of the cover so as to occupy the retaining position.
According to the fourth aspect of the invention, the retaining member can be fixed to the housing even after, as well as before, the cover is mounted. Namely, after the cover has been mounted, the extension located outside the cover is grabbed so that the retaining member is inserted into the interior of the cover through the gap formed by elastically deforming the cover so mounted so as to be set at the retaining position, and thereafter the extension can be fixed to the housing outside the cover.
As a result, in addition to the advantage provided under the third aspect of the invention, the retaining member is inserted into the interior of the cover through the gap formed between the cover and the mating surface of the housing when the cover is elastically deformed, and after the retaining member is set at the retaining position, the retaining member is fixed with the extension located outside the cover. Thus, the retaining member can be mounted even after the cover has been mounted. For example, in a case where it is found out that the retaining member is not mounted after the cover has been mounted, since the retaining member can be mounted without removing the cover, the working efficiency in mounting the retaining member can advantageously be improved.
According to the fifth aspect of the invention, there is provided a machine having an oil seal as set forth in the first aspect of the invention, wherein the confirmation means is an opening formed in the cover for allowing the retaining member to be seen therethrough.
According to the fifth aspect of the invention, whether or not the retaining member is mounted can easily be confirmed by seeing through the opening formed in the cover. As a result, in addition to the advantage provided under the first aspect of the invention, the confirmation that the retaining member is mounted can advantageously be eased with the simple construction in which the opening is formed in the cover.
According to the sixth aspect of the invention, there is provided a machine having an oil seal as set forth in any of the first to fifth aspects of the invention, wherein the retaining member which is to be fixed to the housing by the fixing member is a retaining plate formed of a sheet material, and wherein a curved portion is formed on the retaining plate for engagement with an engagement portion provided on the housing to thereby prevent the rotation thereof.
According to the sixth aspect of the invention, the rigidity of the retaining plate formed of a sheet material is enhanced by forming the curved portion, and the rotation of the retaining plate is prevented through engagement of the curved portion with the engagement portion. As a result, in addition to the advantages provided under the cited aspects of the invention, the following advantage can be provided. Namely, since the rigidity of the retaining plate formed of a sheet material is enhanced by forming the curved portion, the thickness of the retaining plate can be reduced and hence the weight thereof can be reduced in turn. On top of that, since the rotation of the retaining member is prevented by making use of the curved portion in such a manner that the curved portion is brought into engagement with the engagement portion, when compared with a case in which the rotation of the retaining plate is prevented using the fixing member, the rotation of the retaining plate can be implemented through the engaging operation which requires a shorter length of time, thereby improving the working efficiency in mounting the retaining plate.
Note that when used in this specification, the axial direction means a direction of a rotating axis of the rotating shaft (in the following first to fourth embodiments, a balance shaft).